In recent years, a secondary battery, which can be repeatedly charged and discharged, has been widely used as an energy source for wireless mobile devices. In addition, the secondary battery has attracted considerable attention as an energy source for electric vehicles and hybrid electric vehicles, which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles that use fossil fuels. As a result, kinds of applications using the secondary battery are being increased owing to advantages of the secondary battery, and hereafter the secondary battery is expected to be applied to more applications and products than now.
Based on the construction of electrodes and an electrolyte, the secondary battery may be classified as a lithium ion battery, a lithium ion polymer battery, or a lithium polymer battery. In particular, the lithium ion polymer battery has been increasingly used because the lithium ion polymer battery has a low possibility of electrolyte leakage and can be easily manufactured.
Based on the shape of a battery case, the secondary battery may also be classified as a cylindrical battery having an electrode assembly mounted in a cylindrical metal can, a prismatic battery having an electrode assembly mounted in a prismatic metal can, or a pouch-shaped battery having an electrode assembly mounted in a pouch-shaped case made of an aluminum laminate sheet.
The secondary battery is being widely used as an energy source for diverse electronic products as well as various kinds of mobile devices. However, various kinds of combustible materials are contained in the secondary battery. As a result, the lithium secondary battery may overheat or explode due to the overcharge of the secondary battery, the overcurrent in the secondary battery, or other external physical impact applied to the secondary battery.
For this reason, the secondary battery is provided with a safety system, such as a protection circuit for interrupting electric current when the secondary battery is overcharged or overdischarged or when overcurrent flows in the secondary battery, a positive temperature coefficient (PTC) element whose resistance greatly increases so as to interrupt electric current when the temperature of the secondary battery increases, or a safety vent for interrupting electric current or exhausting gas when pressure increases due to generation of the gas. Meanwhile, a multi-cell type middle or large-sized battery pack, which is configured to have a multi-cell structure in which a plurality of battery modules is combined, is provided with a safety system, such as a fuse, a bimetal, or a battery management system (BMS), for protecting battery cells from overcharge, overdischarge, or overcurrent.
The safety system is connected to voltage sensing terminals via wires so as to detect voltages of battery cells or unit modules.
FIG. 1 is a typical view showing a conventional battery module in which an adhesive is used to fix voltage sensing wires.
Referring to FIG. 1, voltage sensing terminals 30 for voltage detection is formed on the upper surface of a battery module 10. Wires 50 are connected to the voltage sensing terminals 30. An adhesive 60 is applied so as to fix the wires 50, which extend from the middle to one side of the battery module.
In this structure, the voltage sensing terminals and the wires are soldered, and the adhesive is applied so as to fix the wires. Alternatively, the wires may be fixed using an adhesive tape.
In the case in which the wires are fixed using the adhesive or the tape, the aesthetic appearance of the battery module is greatly deteriorated, with the result that consumers' reliability and satisfaction are lowered.
In addition, the adhesive may not be applied uniformly or may not be applied to improper positions. In this case, the wires may not be fixed uniformly, whereby the wire may be separated when the manufacturing process is performed on a conveyor line.
Furthermore, material cost and manufacturing cost may be increased due to the use of the adhesive, and the manufacturing process is performed irregularly, with the result that tact time may be increased.